Application Of Floating Bead Biofilter In Recirculating Rainbow Trout Culture System

This paper inroduces the application of floating bead biofilter in recirculating rainbow trout culture system.This system includes the oxygen injection,the solid depositing separation and the two- layer floating bead biofiltration.The two—layer floating head biofilter could filtrate 90% suspended sol- ids and the ability of treating ammonia—nitrogen is 149g.m-3.d-1 when the temperature is 15℃.Ozone catalyzing oxidation could disinfect and remove ammonia-nitrogen one more time.In a recireulating sys- tem of 12 m3 water and 30kg/m3 culture density,we utilized a set of BAF-40 two-layer floating head biofilter with 0.75kW power and 20T/h to treat the culture water for reuse.During culture period,pH, DO,COD,SS,ammonia,nitriteand nitrate and so on were analyzed and the length and weight of culture rainbow trout were measured.The result showned that if the period of the water recycle was 2 hours and water exchange period was a week,the water quality was good and COD≤15mg/l,ammonia≤lmg/l, nitrite≤0.13mg/l,nitrate≤24mg/l.After 2 weeks contrast culture experiment,comparing the parame- ter of culture water that streamed through the biofilter,the other culture water parameters is very differ- ent.The experiment showed that the floating bead biofilter can be successfully used in reeirculating rain- bow trout culture system to meet the rainbow trout culture need of water and biology.